The present invention generally relates to programmable thermostats and, more particularly, to a thermostat display for an electronic programmable thermostat having a temperature recovery system.
Attempts to develop improved heating and cooling systems generally focus on improved efficiency coupled with reduced cost. One technique which attempts to embody these concepts is temperature setback and recovery. Generally, setback refers to the concept of lowering the setpoint temperature of a thermostat during night time periods or periods when the region controlled by the thermostat is unoccupied in order to reduce the energy required to heat the controlled region. A related concept called set-up refers to the raising of the setpoint temperature of a thermostat during periods of nonoccupancy of the controlled region in order to reduce the energy required to cool the region. Finally, recovery refers to the concept of activating a heating or cooling system so as to raise (or lower) the temperature at the end of setback (or setup) to some predetermined temperature.
Studies conducted by the Department of Energy estimate that setting a thermostat back 10.degree. F. for two eight-hour periods during winter can reduce a user's energy costs by as much as 35%. Setting a thermostat up 5.degree. for two eight-hour periods during summer can reduce a user's energy costs by up to 25%. For example, a thermostat may be programmed to raise the ambient room temperature from a setback temperature of 60.degree. F. to a programmed temperature of 68.degree. F. by 6 a.m. In a thermostat which has a built-in recovery system, the heating system will begin operating at sometime prior to 6 a.m. so that by 6 a.m., the ambient temperature will be 68.degree. F.
However, when temperature recovery begins and the heating system is activated, a user may wonder why the heating system is not operating in accordance with the current program temperatures. This may cause a user to believe that his thermostat and heating system are malfunctioning. A similar situation can result when the cooling system attempts to lower the ambient temperature by initiating recovery prior to the subsequent program time.